Integrated delivery and visualization tool for a neuromodulation system

ABSTRACT

Methods and apparatus for delivering a neurostimulator to a target tissue are provided which may include any number of features. One feature is a delivery tool comprising a handle portion, an elongate shaft comprising a contoured distal portion, a visualization system embedded in the elongate shaft, and an insertion groove on the elongate shaft configured to deploy the neurostimulator. The contoured distal portion can be shaped and configured to maintain contact with a posterior maxilla and elevate a periosteum off of the posterior maxilla to avoid soft tissue dissection. In some embodiments, the neurostimulator is implanted in close proximity to or touching the sphenopalatine ganglion.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. 119 of U.S. Provisional Patent Application No. 61/141,179, filed Dec. 29, 2008, titled “INTEGRATED DELIVERY AND VISUALIZATION TOOL FOR A NEUROMODULATION SYSTEM.” This application is herein incorporated by reference in its entirety.

INCORPORATION BY REFERENCE

All publications, including patents and patent applications, mentioned in this specification are herein incorporated by reference in their entirety to the same extent as if each individual publication was specifically and individually indicated to be incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to a surgical tool and visualization method for delivering a therapy delivery device to craniofacial regions, and more specifically to a surgical tool and integral visualization method for delivery of a neurostimulator device to the pterygopalatine fossa (PPF).

BACKGROUND OF THE INVENTION

Electrical stimulation of peripheral and central neural structures has shown increased interest due to the potential benefits it may provide to individuals suffering from many neurological and behavioral diseases. Many of these therapies today are not well accepted due to the invasive nature of the therapy, even though the efficacy is quite good. This has created a need for less invasive therapies that are directed toward patient and physician clinical needs.

Headaches are one of the most debilitating ailments that afflict millions of individuals worldwide. The specific pathophysiology of headaches is unknown. Known sources of headache pain consist of trauma, vascular, autoimmune, degenerative, infectious, drug and medication-induced, inflammatory, neoplastic, metabolic-endocrine, iatrogenic, musculoskeletal and myofacial causes. Also, even though the possible underlying cause of the headache pain is identified and treated, the headache pain may persist.

Currently, the sphenopalatine (pterygopalatine) ganglion (SPG) is a target of manipulation in clinical medicine to treat headaches. The SPG is an extracranial neuronal center located behind the nose. It consists of parasympathetic neurons that innervate (in part) the middle cerebral and anterior cerebral blood vessels, the facial blood vessels, and the lacrimal glands. The SPG also consists of sympathetic and sensory nerve fibers that pass through the SPG in route to their end organs. Manipulation of the SPG is mostly performed in attempted treatments of severe headaches, such as cluster headaches or chronic migraines.

Various clinical approaches have been used for over 100 years to modulate the function of the SPG to treat headaches. These procedures vary from least invasive (e.g. transnasal anesthetic blocks) to much more invasive (e.g. surgical ganglionectomy) as well as procedures such as surgical anesthetic injections, ablations, gamma knife and cryogenic surgery. Most of these procedures have very good short term efficacy outcomes (days to months), however these results are usually temporary and the headache pain returns. A chronically implanted SPG neurostimulator may provide much better long term efficacy in these patients.

SUMMARY OF THE INVENTION

In one embodiment, a method of delivering a neurostimulator to within close proximity of a sphenopalatine ganglion is provided, comprising making an incision over the anterior maxilla, inserting a delivery tool having an integrated visualization system into the incision, visualizing tissue near a distal portion of the delivery tool with the visualization system, advancing the delivery tool sub-periosteally at a lateral edge of a zygomaticomaxillary buttress region towards a pterygopalatine fossa, and delivering the neurostimulator in close proximity to the sphenopalatine ganglion.

The method can further comprise the step of elevating a periosteum away from the anterior maxilla with the delivery tool to expose a zygomaticomaxillary buttress region prior to the advancing step. In some embodiments, the advancing step further comprises advancing the delivery tool posteriorly, medially, and superiorly towards the pterygopalatine fossa.

In one embodiment, the delivery tool includes a contoured distal portion that is shaped and configured to maintain contact with a posterior maxilla and elevate a periosteum off of the posterior maxilla to avoid soft tissue dissection. The contoured distal portion can have a thickness of between 2-5 mm, for example. In some embodiments, the contoured distal portion has an elliptical cross-section.

In one embodiment, the visualization system comprises a fiberscope.

In some embodiments, the method further comprises the step of illuminating the delivery tool with a light source placed within a nasal cavity and positioned close to or within a sphenopalatine foramen.

A delivery tool configured to deliver a neurostimulator into a patient is also provided, comprising a handle portion, an elongate shaft comprising a contoured distal portion, the contoured distal portion shaped and configured to maintain contact with a posterior maxilla and elevate a periosteum off of the posterior maxilla to avoid soft tissue dissection, a visualization system embedded in the elongate shaft, and an insertion groove on the elongate shaft configured to deploy the neurostimulator.

In some embodiments, the insertion groove is recessed into the elongate shaft. In other embodiments, the insertion groove is located on an opposing edge of the delivery tool from the visualization system, allowing for visualization of the deployment of the neurostimulator.

In some embodiments, the visualization system is a fiberscope. In other embodiments, the visualization system comprises a light source contained in the handle portion.

In one embodiment, the delivery tool further comprises a lens embedded at the distal portion, the lens constructed to allow for a focal length of between 2-15 mm.

In other embodiments, the visualization system is configured to highlight differences between soft tissue and bone. In another embodiment, the visualization system comprises an electronic chip positioned within the distal portion and configured to provide video and/or still images to be sent to a viewing system.

In one embodiment, the delivery tool further comprises an external light source configured to provide transillumination of the delivery tool. In another embodiment, the delivery tool further comprises an aperture configured to dispense a fluid to a distal end of the delivery tool. The delivery tool can further comprise a touch sensitive button coupled to the aperture, wherein a quick press of the button releases a bolus of fluid and a long press of the button releases a continuous stream of fluid.

In some embodiments, the delivery tool further comprises a bifurcated distal dissecting tip having a lens positioned between the dissecting tips.

In additional embodiments, the delivery tool further comprises a tissue clearance tip around the visualization system configured to provide increased tissue clearance around the visualization system.

In some embodiments, the contoured distal portion has a thickness of between 2-5 mm. In other embodiments, the contoured distal portion has an elliptical cross-section.

A method of treating a neurological disorder is also provided, comprising making an incision over an anterior maxilla, inserting a delivery tool having an integrated visualization system into the incision, visualizing tissue near a distal portion of the delivery tool with the visualization system, advancing the delivery tool sub-periosteally at a lateral edge of the zygomaticomaxillary buttress region towards the pterygopalatine fossa, delivering the neurostimulator in close proximity to the sphenopalatine ganglion, and applying an electrical current from the neurostimulator to the sphenopalatine ganglion to treat the neurological disorder.

In some embodiments, the method further comprises the step of elevating a periosteum away from the anterior maxilla with the delivery tool to expose a zygomaticomaxillary buttress region prior to the advancing step.

In another embodiment, the delivery tool includes a contoured distal portion that is shaped and configured to maintain contact with a posterior maxilla and elevate a periosteum off of the posterior maxilla to avoid soft tissue dissection.

In some embodiments, the neurological disorder is headache.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a lateral looking view of the target anatomy.

FIG. 2 is a front looking view of a delivery and visualization tool.

FIG. 3 is an isometric view of the integral delivery and visualization tool.

FIG. 4 a is a detailed isometric view of the distal tip of the tool.

FIG. 4 b is a cross-section of the distal tip of the tool.

FIG. 5 is an isometric view of an alternate embodiment of a bifurcated distal tip of the tool.

FIG. 6 is an isometric view of a lens covering shown engaging the fiber lens on the distal tip of the tool.

FIG. 7 is an enlarged isometric view of an alternate embodiment of the distal tip housing a digital video camera.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2 illustrates an embodiment of an integrated delivery and visualization tool 100 shown positioned within the craniofacial anatomy. The tool can be used in aided delivery of a small neurostimulator for the treatment of chronic headaches. The tool is designed and constructed to elevate and or dissect the periosteum and soft tissue, and to visualize the intended anatomy, as illustrated in FIG. 1, during delivery of the neurostimulator. The tool is designed to be inserted trans-orally from an incision located on the anterior maxilla 101. The tool can then elevate the periosteum away from the anterior maxilla bone 101 to expose the zygomaticomaxillary buttress region 103. The tool can then be inserted sub-periosteally at the lateral edge of the zygomaticomaxillary buttress and advanced posteriorly, medially, and superiorly towards the PPF 104. The SPG 105, a small extracranial autonomic ganglion, is located within the PPF. The SPG is the intended target for stimulation for the treatment of headaches and other neurological disorders. This tool is designed and configured to deliver the neurostimulator in very close proximity to the SPG, by contacting the SPG directly or by placing the neurostimulator within 1-5 mm of the SPG, such that targeted electrical stimulation or delivery of electrical current from the neurostimulator to the SPG can be accomplished.

In one embodiment, as shown in FIG. 3, the tool 100 features an elongate shaft comprising a compound-contoured distal portion 110 with an integral visualization system 140. Using an integral visualization system in the delivery tool advantageously reduces or eliminates radiation exposure in the patient since fewer or no x-rays or fluoroscopy are needed. The tool can be made of surgical grade stainless steel, for example. In one embodiment the tool is approximately 15-40 cm in length, excluding the visualization viewing system attachments. The distal portion 110 of the tool can be shaped and configured such that a user can maintain contact with the posterior maxilla while advancing the tool sub-periosteally to the pterygopalatine fossa. The tool is shaped and designed to maintain bone contact and elevate the periosteum off the bone to avoid soft tissue dissection, which may prevent unwanted soft tissue injury or bleeding during the implantation of a neurostimulator. Additionally, by remaining sub-periosteal, a higher contrast between the bone and the soft tissue overlaying the periosteum can make visualization easier.

In one embodiment, the visualization system comprises a fiberscope 140 embedded into the elongate shaft of the delivery tool, as shown in FIG. 3. The fiberscope allows for both illumination and visualization of tissue near the distal end of the delivery tool. The fiberscope can contain two types of fiber optic bundles, such as fiber optic light bundles for illumination and fiber optic image bundles to relay images to the viewing system. The number of fibers within the fiberscope visualization system is dependent on the overall diameter of each fiber and the overall diameter of the fiberscope, which is dependent on the size and shape of the delivery tool.

In some embodiments, the delivery tool's distal portion 110 can have a thickness of between 2-5 mm, with a fiberscope diameter that corresponds to the thickness of the delivery tool (2-5 mm). More specifically, the distal portion of the tool can be 3 mm thick with a fiberscope diameter of 2 mm. The tool's distal portion 110 can have a radius of curvature ranging from 8 cm to 0.3 cm. In one specific embodiment, the radius of curvature of the distal portion can be approximately 4.5 cm, and in another embodiment, the radius of curvature of the tool's distal portion can be nearly flat. The illumination fibers within the fiberscope can accommodate a number of different light sources, including, but not limited to, white, red, blue, green, infrared, and near infrared light sources. In some embodiments, the light sources are contained within the delivery tool and more specifically within the handle of the delivery tool.

The light sources may be light emitting diodes or other standard light sources that can be contained in the handle of the delivery tool. Also in some embodiments, the light sources are selectable as individual sources or in combination sources used in conjunction. The different light sources may allow for differentiation of different tissue types, for example, bone, fat, blood vessels, and nerves, where blue light is preferred for achieving good contrast between nerves and other tissues.

A lens can also be embedded at the distal portion of the delivery tool, the lens being constructed to allow for maximum viewing angle at the tip of the delivery tool. In some embodiments, the lens can allow for a focal length of between 2-15 mm. More specifically, since the depth of the PPF is variable but likely between 10 and 20 mm deep, and the location of the SPG within the PPF is between 4 and 10 mm from the medial wall of the PPF, a viewing distance or focal length of 5-7 mm will likely cover the range needed with the distal portion of the delivery tool at or just within the opening of the PPF.

The fiberscope can then be attached to a viewing system 150, as shown in FIG. 3. The viewing system 150 can be a standard video display with the necessary electronics to convert the image from the fiberscope to a real time video display. Alternatively, a customized viewing system can be made that includes advanced image processing capabilities to help guide implantation, for example, by highlighting the differences between soft tissue and bone. The advanced image processing may include the ability to detect and process non-visible wavelengths, such as, but not limited to, infrared and near-infrared.

In an alternative embodiment, a separate light source may be used in conjunction with or solely to help illuminate and visualize the target anatomy. The PPF is located behind the nose and is constrained anteriorly by the posterior maxilla, medially by the sphenoid bone, posteriorly by the pterygoid process and laterally open to the infratemporal fossa. Additionally the PPF can be accessed from the nasal cavity via the sphenopalatine foramen or laterally from the infratemporal fossa. A light source can be placed within the nasal cavity and positioned close to or within the sphenopalatine foramen to provide illumination of the tool. The light source can include, but is not limited to, white, red, blue, green, infrared, and near infrared light sources. Additionally, to aid in the placement of the neurostimulator within very close proximity to the SPG, additional working channels can be utilized though the nasal cavity for additional tools to help pull the neurostimulator into the correct placement or make small adjustments to the final location of the neurostimulator.

In an additional embodiment, an external bright light source may also be used in conjunction with or solely to help illuminate and visualize the target anatomy. The PPF is open on its lateral aspect to the infratemporal fossa, thus a bright light may be placed on the external skin, and more specifically, on the cheek or forehead either in or out of a dark room to transilluminate the target anatomy PPF. Transillumination is a procedure used for medical diagnostic purposes to visualize the maxillary and frontal sinuses to rule out any problems in these areas. Since the PPF is located just posterior to the maxillary sinus and inferior to the frontal sinuses, transillumination in this area may provide an adequate light source for visualization of the PPF and more specifically the SPG. The bright light source used can include, but is not limited to, white, red, blue, green, infrared, and near infrared light sources.

The compound-contoured distal portion comprises a curvilinear body having an elliptical cross-section, with a sharpened edge at the distal tip of the curvilinear body that is configured to contact the bone and dissect through the tissue. The distal edge can be configured and shaped to traverse around the zygomaticomaxillary buttress and under the zygomatic bone along the posterior maxilla and into the pterygopalatine fossa, while maintaining contact with the posterior maxilla 102, as labeled in FIG. 1, and lifting the periosteum off the posterior maxilla.

According to this embodiment the tool can also include an insertion groove 120 in the elongate shaft. The insertion groove is recessed into the elongate shaft and configured to guide and/or deploy the neurostimulator into the pterygopalatine fossa to within close proximity of the target neural anatomy, such as the SPG. Once the tool is place in position within the PPF and in close proximity to the SPG, the distal end of the neurostimulator is placed within the proximal portion of the insertion groove on the tool and advanced. The neurostimulator is advanced by pushing the neurostimulator along the insertion groove into the PPF. In one embodiment, the insertion groove 120 is located on the opposing edge of the delivery tool from the fiberscope and fiberscope lens 140, allowing for visualization of the deployment of the neurostimulator into the target anatomy.

Also according to this embodiment, the tool incorporates an ergonomic handle 130 of approximately 6-12 cm in length, varying in diameter from proximal (0.5-3 cm) to distal (0.5-2 cm), with variable methods to provide grip and tactile manual maneuverability, such as circumferential ridges or cross-hatched precut pattern into the surgical grade stainless steel. In one embodiment, the handle and shaft of the delivery tool can contain the flexible fiberscope within the body of the tool.

FIG. 4 a shows a close-up view of the curvilinear geometry of the distal portion 110 of the integral delivery and visualization tool 100. As illustrated in FIG. 4 a, the tool incorporates an insertion or deployment groove 120, a tissue dissecting tip 160, an integral fiberscope visualization system 170, and an aperture 180. The aperture can be used to dispense saline to the distal tip of the tool, providing a gap between the tissue and the visualization system's lens. A piece of plastic (or other transparent material) can also provide a gap between the lens and the tissue. The aperture could also be used to remove fluid from the tip of the device, for example, blood.

The delivery of fluid through the aperture can be done from a syringe based system, which can be attached to the delivery tool. However, in one embodiment, the delivery and visualization tool maintains a refillable volume of fluid within the handle. The fluid can be deployed into the visualization field using an integral button on the handle of the delivery tool. The button can be touch sensitive, such that a quick press releases a bolus of fluid into the visualization field, and a long press delivers a continuous stream of fluid into the visualization field to clear and create tissue separation for increased visualization. Alternatively, fluid can be delivered by a control system attached to the tool, or manually by the user, for example, using standard IV drip lines. The stored fluid can be normal saline, or other physiological solutions, such as sterile water. The stored fluid can also be or contain a therapeutic or diagnostic agent, such as but not limited to vasocontrictive agents or a local anesthetic, such as lidocaine, or other types of drugs used to create local anesthetic blocks. The fluid can be delivered from the distal tip of the tool through a larger lumen that contains the fiberscope, according to some embodiments. Alternatively, the fluid can be delivered to the tip of the tool through a small lumen or catheter that is integrated to the shaft of the tool. The same system can also be used to remove fluid, for example, blood or saline, using external suction.

In one embodiment, the distal portion 110 of the tool also incorporates a curvilinear geometry along the axis of the tool. The curvilinear geometry can range between 2.5 cm and 7.5 cm. The distal curve of the tool is designed to allow maximal engagement of the posterior maxilla as the delivery tool is advanced posteriorly, medially and superiorly into the PPF of human patients of different anatomical sizes, while minimizing tissue damage by dissecting the plane between the bone and the periosteum. The sculpted distal portion of the tool tapers to the distal tip, which maintains contact with the bone and can be generally elliptically shaped in cross-section, as shown in FIG. 4 b.

In one embodiment, as shown in FIG. 4 b, the embedded fiberscope can be located centrally within a lumen 220 in the cross-section of a delivery tool 200. Also according to this embodiment, the aperture for fluid delivery has a separate lumen 220. In this embodiment each lumen runs the length of the delivery tool. The lumen for the fiberscope and aperture can be located away from the insertion or deployment groove 120.

In FIG. 4 b, the distal tip of the integral delivery and visualization system is adapted to taper to a sharp edge that is similar to standard surgical periosteal elevators. At the distal tip, the final 5-15 mm of the tip may have an increased curvature in the same plane as the distal portion curvature of the tool. This increased curvature at the tip is done to allow greater contact with the posterior maxilla as the delivery tool is advanced toward the PPF. Also, this curvature creates increased amount of tissue separation that allows for increased amount of visualization of the target anatomy. Also according to this embodiment and the primary embodiment, as the distal tip tapers to the distal edge, the lumen for the fiberscope is stopped such that the distal edge and the fiberscope lens are not in the same plane, but the fiberscope lens is more proximal from the distal tip. Alternatively, a clear glass can be used to fill in the gap between the distal edge and the lens from the fiberscope, or the gap can be filled in by a custom made lens. In yet another embodiment, individual fibers from the fiberscope can extend to the distal edge of the tool so that no gap exists between the individual fibers and the lens at the distal edge of the tool.

In an alternative embodiment, as illustrated in FIG. 5, the tool 100 may include a bifurcated distal dissecting tip 230, with a lens 240 centered or arranged between the tissue dissecting members. Alternate embodiments of the tool include various tips of various shapes and configurations to either bluntly or sharply dissect the periosteum from the bone and include visualization of the target anatomy.

In other embodiments of the tool, the shaft and tool tip can be manufactured from various other materials: metals such as titanium and rigid polymers such as PEEK, polycarbonate, or nylon. The tool may also be made from ceramics such as aluminum oxide or zirconium oxide. Additionally, the tool may be made from combinations of metals, ceramics, plastics or plastic composites. Alternate embodiments of the tool include tips that are removable from the tool for disposal or exchanged for different tip, such as tips with different curvatures, dissecting edges, and visualization lens.

Another embodiment of the integrated delivery and visualization tool includes a fiber optic scope that is used as auxiliary equipment to the tool and engages and disengages as required. The fiber optic scope in this embodiment is used to visualize surrounding tissue and the SPG as the tool advances across the posterior maxilla and into the PPF.

As illustrated in FIG. 6, a distal portion 110 of the tool can support an additional clearance tip 175 configured to provide increased tissue clearance around the fiberscope visualization system for greater visualization of the target tissue. The tissue clearance tip 175 can be fitted onto the tip of the fiberscope and can be made from either polymers or plastics that have an optically transparent and non distorting finish to provide the greatest visualization of the surrounding tissue.

As illustrated in FIG. 7, an alternate embodiment of the distal portion 110 of the tool includes a miniature digital electronic chip 260 and a miniature light emitting diode 270, either integral within the distal portion of the integrated delivery and visualization tool or on the elongate shaft of the tool, and containing a lens or prism and lens that is directed forward to visualize the target anatomy. The digital chip can provide video and or still images to be sent to a viewing system. The digital chip can be linked to the viewer system either using a wired or wireless connection. The viewing system can be a standard external video display, and small handheld display, or integrated into a heads up display located on a pair of glasses worn by the user. The viewing system can be used as part of any or all of the embodiments described in this application.

In an alternate embodiment, either in addition to or instead of the visualization system, a contact switch can be included at or near the distal portion of the delivery tool, such that it is nominally in contact with bone. The switch could be mechanical, like a reed switch, or electrical, like a capacitive proximity sensor, and can communicate contact with bone to the user when deformed. Communication can be achieved audibly, for example with an alarm, visibly, for example with a light, or mechanically, for example with a button that pops up. Further, if a visualization system is being used, an alert can be communicated on the monitoring screen.

In an additional embodiment, the tool may be designed to allow safe transmission of RF (radiofrequency) energy without affecting the safety of the patient or efficacy of the tool. Transmitting RF energy to achieve hemostasis by coagulating bleeding vessels is a common surgical technique. By designing the tool to safely transmit RF energy, the surgeon can coagulate undesirably bleeding vessels and or tissues without removing the tool. In order to achieve this, all but the areas desired for RF delivery would be electrically insulated from the patient and the user to prevent RF energy from affecting undesired areas in the patient or the user.

As for additional details pertinent to the present invention, materials and manufacturing techniques may be employed as within the level of those with skill in the relevant art. The same may hold true with respect to method-based aspects of the invention in terms of additional acts commonly or logically employed. Also, it is contemplated that any optional feature of the inventive variations described may be set forth and claimed independently, or in combination with any one or more of the features described herein. Likewise, reference to a singular item, includes the possibility that there are plural of the same items present. More specifically, as used herein and in the appended claims, the singular forms “a,” “and,” “said,” and “the” include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation. Unless defined otherwise herein, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The breadth of the present invention is not to be limited by the subject specification, but rather only by the plain meaning of the claim terms employed. 

What is claimed is:
 1. A method of delivering a neurostimulator to within close proximity of a sphenopalatine ganglion, comprising: making an incision over an anterior maxilla; inserting a delivery tool having an integrated visualization system into the incision; visualizing tissue near a distal portion of the delivery tool with the visualization system; advancing the delivery tool sub-periosteally at a lateral edge of a zygomaticomaxillary buttress region towards a pterygopalatine fossa; and delivering the neurostimulator in close proximity to the sphenopalatine ganglion.
 2. The method of claim 1 further comprising the step of elevating a periosteum away from the anterior maxilla with the delivery tool to expose a zygomaticomaxillary buttress region prior to the advancing step.
 3. The method of claim 1 wherein the advancing step further comprises advancing the delivery tool posteriorly, medially, and superiorly towards the pterygopalatine fossa.
 4. The method of claim 1 wherein the delivery tool includes a contoured distal portion that is shaped and configured to maintain contact with a posterior maxilla and elevate a periosteum off of the posterior maxilla to avoid soft tissue dissection.
 5. The method of claim 4 wherein the contoured distal portion has a thickness of between 2-5 mm.
 6. The method of claim 4 wherein the contoured distal portion has an elliptical cross-section.
 7. The method of claim 1 wherein the visualization system comprises a fiberscope.
 8. The method of claim 1 further comprising the step of illuminating the delivery tool with a light source placed within a nasal cavity and positioned close to or within a sphenopalatine foramen.
 9. A method of treating a neurological disorder, comprising: making an incision over an anterior maxilla; inserting a delivery tool having an integrated visualization system into the incision; visualizing tissue near a distal portion of the delivery tool with the visualization system; advancing the delivery tool sub-periosteally at a lateral edge of the zygomaticomaxillary buttress region towards the pterygopalatine fossa; delivering the neurostimulator in close proximity to the sphenopalatine ganglion; and applying an electrical current from the neurostimulator to the sphenopalatine ganglion to treat the neurological disorder.
 10. The method of claim 9 further comprising the step of elevating a periosteum away from the anterior maxilla with the delivery tool to expose a zygomaticomaxillary buttress region prior to the advancing step.
 11. The method of claim 9 wherein the delivery tool includes a contoured distal portion that is shaped and configured to maintain contact with a posterior maxilla and elevate a periosteum off of the posterior maxilla to avoid soft tissue dissection.
 12. The method of claim 9 wherein the neurological disorder is headache. 